@import url('https://fonts.googleapis.com/css2?family=DM+Sans:wght@400;500;600;700&display=swap');
:root{--ink:#17191e;--secondary:#626873;--blue:#2451ec;--rule:#e5e7ed;--paper:#fff;--rail:#f7f8fb;--sans:'DM Sans',Arial,sans-serif}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:40px}body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--sans);-webkit-font-smoothing:antialiased}button,a{-webkit-tap-highlight-color:transparent}a{color:inherit}button{font:inherit;cursor:pointer}button:focus-visible,a:focus-visible{outline:3px solid var(--blue);outline-offset:5px}::selection{background:#dbe4ff}button{color:inherit}.skip{position:fixed;top:-100px;left:20px;z-index:50;background:var(--ink);color:white;padding:15px}.skip:focus{top:20px}
.sidebar{width:244px;position:fixed;inset:0 auto 0 0;background:var(--rail);border-right:1px solid var(--rule);padding:34px 23px 24px;display:flex;flex-direction:column;z-index:20}.author{font-size:17px;text-decoration:none;font-weight:700;letter-spacing:-.04em;display:block}.author span{color:var(--blue)}.rail-label{font-size:12px;font-weight:600;text-transform:uppercase;letter-spacing:.13em;color:var(--secondary);margin:7px 0 45px}.contents-label{font-size:12px;letter-spacing:.13em;color:var(--secondary);text-transform:uppercase;margin:0 0 18px}.chapter-nav{flex:1;min-height:0;overflow-y:auto;scrollbar-width:thin}.nav-chapter{margin-bottom:10px}.chapter-link{display:flex;gap:13px;align-items:baseline;text-decoration:none;padding:10px 0;font-size:14px;line-height:1.45;font-weight:500}.chapter-link .num{font-size:12px;color:#828793;font-variant-numeric:tabular-nums;min-width:17px}.nav-chapter.is-active>.chapter-link{color:var(--blue)}.nav-chapter.is-active>.chapter-link .num{color:var(--blue)}.subnav{display:none;margin:2px 0 20px 30px;border-left:1px solid #d9dde7;padding-left:13px}.nav-chapter.is-active .subnav{display:block}.subnav a{display:block;text-decoration:none;color:var(--secondary);font-size:13px;line-height:1.5;padding:5px 0}.subnav a[aria-current=location]{color:var(--blue);font-weight:600}.rail-bottom{padding-top:20px;margin-top:15px;border-top:1px solid var(--rule)}.progress-label{display:flex;justify-content:space-between;font-size:12px;color:var(--secondary);margin-bottom:10px}.track{height:2px;background:#dde0e8;overflow:hidden}.track span{display:block;width:0;height:100%;background:var(--blue)}.motion-toggle{margin-top:18px;border:0;background:transparent;padding:3px 0;color:var(--secondary);font-size:12px;text-align:left;display:flex;align-items:center;gap:8px}.motion-indicator{width:7px;height:7px;border:1px solid currentColor;border-radius:50%}.motion-toggle[aria-pressed=true] .motion-indicator{background:var(--blue);border-color:var(--blue)}
.mobile-bar{display:none}.page{margin-left:244px;padding:36px 54px 0;max-width:1560px}.topline{display:flex;justify-content:space-between;align-items:center;border-bottom:1px solid var(--rule);padding-bottom:20px;font-size:12px;letter-spacing:.11em;text-transform:uppercase}.topline .category{color:var(--secondary)}.topline .edition{color:var(--blue)}.hero{padding:58px 0 70px;border-bottom:1px solid var(--ink);position:relative}.eyebrow{color:var(--blue);font-size:13px;letter-spacing:.13em;text-transform:uppercase;font-weight:500;margin:0 0 24px}.hero h1{font-size:clamp(58px,6.8vw,108px);line-height:1.03;letter-spacing:-.065em;margin:0;max-width:900px;font-weight:500}.hero h1 .revenue{display:block;color:var(--blue);white-space:nowrap;margin-top:2px}.hero-lower{display:grid;grid-template-columns:minmax(0,1.5fr) minmax(220px,1fr);align-items:center;gap:35px;margin-top:35px}.hero-description{font-family:Georgia,serif;font-size:21px;line-height:1.65;max-width:550px;margin:0 0 24px}.meta{font-size:12px;color:var(--secondary);display:flex;gap:22px;flex-wrap:wrap;align-items:center}.meta strong{font-weight:500;color:var(--ink)}.hero-figure{margin:0;transform:rotate(-3deg)}.hero-figure canvas{height:180px;width:100%;display:block}.hero-figure figcaption{font-family:Georgia,serif;font-style:italic;font-size:13px;color:var(--secondary);text-align:center;margin-top:0}.start-link{display:inline-block;margin-top:32px;color:var(--blue);font-size:14px;text-decoration-thickness:1px;text-underline-offset:5px}
.chapter{padding:66px 0 28px;border-bottom:1px solid var(--rule);scroll-margin-top:30px}.chapter-heading{display:flex;align-items:baseline;gap:20px;margin-bottom:34px}.chapter-index{font-size:14px;color:var(--blue);font-variant-numeric:tabular-nums}.chapter h2{font-weight:500;font-size:clamp(32px,3.4vw,47px);line-height:1.13;letter-spacing:-.045em;margin:0}.chapter-intro{font-family:Georgia,serif;font-size:19px;line-height:1.75;max-width:610px;margin:0 0 38px}.lesson{display:grid;grid-template-columns:minmax(0,1fr) 250px;gap:36px;padding:12px 0 34px;scroll-margin-top:40px}.lesson+.lesson{padding-top:28px}.lesson h3{font-size:24px;font-weight:500;letter-spacing:-.025em;line-height:1.3;margin:0 0 20px}.lesson p,.lesson li{font-family:Georgia,serif;font-size:18px;line-height:1.85;margin:0 0 20px}.lesson p:last-child{margin-bottom:0}.lesson strong{font-weight:700}.lesson a{color:var(--blue);text-decoration-thickness:1px;text-underline-offset:3px;overflow-wrap:anywhere}.lesson ul{padding-left:22px}.lesson li{margin-bottom:10px}.lesson blockquote{font-family:Georgia,serif;font-size:25px;line-height:1.5;letter-spacing:-.02em;border-left:2px solid var(--blue);padding-left:22px;margin:30px 0}.lesson blockquote p{font:inherit}.sketch{margin:0;align-self:start;position:sticky;top:70px;padding-top:9px}.sketch canvas{width:100%;height:188px;display:block}.sketch figcaption{font-family:Georgia,serif;font-style:italic;color:var(--secondary);font-size:13px;line-height:1.5;text-align:center;padding:0 13px}.stage-list{list-style:none;padding-left:0!important;border-top:1px solid var(--rule)}.stage-list li{display:grid;grid-template-columns:110px 1fr;gap:18px;padding:14px 0;border-bottom:1px solid var(--rule);font-family:var(--sans);font-size:15px;line-height:1.5;margin:0}.stage-list strong{color:var(--blue);font-weight:500}.book-list{list-style:none;padding-left:0!important}.book-list li{padding:15px 0;border-bottom:1px solid var(--rule);margin:0}.book-list strong{display:block;font-family:var(--sans);font-size:17px;font-weight:500;margin-bottom:3px}.book-list span{font-family:Georgia,serif;font-size:17px}.closing{padding:72px 0 85px}.closing p{max-width:750px;font-family:Georgia,serif;font-size:clamp(28px,3vw,40px);line-height:1.45;letter-spacing:-.025em;margin:0 0 34px}.closing a{font-size:14px;color:var(--blue);text-underline-offset:5px}.footer{padding:24px 0 30px;border-top:1px solid var(--rule);display:flex;justify-content:space-between;gap:20px;font-size:12px;color:var(--secondary)}.footer a{text-decoration:none}
@media(min-width:1600px){.page{padding-left:80px;padding-right:80px}.lesson{grid-template-columns:minmax(0,680px) 290px;gap:60px}.hero h1{font-size:120px}.sidebar{width:270px;padding-left:34px;padding-right:28px}.page{margin-left:270px}}
@media(max-width:1180px){.sidebar{width:216px;padding-left:20px;padding-right:16px}.page{margin-left:216px;padding:30px 34px 0}.lesson{grid-template-columns:minmax(0,1fr) 180px;gap:20px}.sketch canvas{height:155px}.hero h1{font-size:clamp(58px,7.4vw,96px)}.hero-lower{gap:10px}.hero-description{font-size:20px}.lesson p,.lesson li{font-size:18px}}
@media(max-width:900px){html{scroll-padding-top:95px}.sidebar{transform:translateX(-100%);width:300px;transition:transform .25s;top:63px;background:white;box-shadow:10px 0 30px #17191e12;padding-top:25px}.sidebar.is-open{transform:translateX(0)}.sidebar .author,.sidebar .rail-label{display:none}.sidebar .subnav{display:block}.mobile-bar{display:flex;position:fixed;inset:0 0 auto 0;background:#fffffff5;backdrop-filter:blur(12px);border-bottom:1px solid var(--rule);height:63px;align-items:center;justify-content:space-between;padding:0 24px;z-index:25;gap:16px}.mobile-bar .author{font-size:16px;white-space:nowrap}.contents-button{background:transparent;border:1px solid var(--rule);padding:7px 12px;font-size:13px;max-width:60%;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.mobile-progress{position:absolute;left:0;bottom:-1px;height:2px;background:var(--blue);width:0}.page{margin-left:0;padding:92px 36px 0;max-width:1000px}.hero h1{font-size:clamp(56px,10.5vw,86px)}.hero{padding-top:44px;padding-bottom:55px}.lesson{grid-template-columns:minmax(0,1fr) 210px;gap:25px}.chapter,.lesson{scroll-margin-top:95px}.scrim{position:fixed;inset:63px 0 0;background:#17191e35;z-index:19}.scrim[hidden]{display:none}.sketch{top:100px}}
@media(max-width:600px){.page{padding:86px 22px 0}.topline{font-size:10px;letter-spacing:.08em;gap:16px}.hero{padding:36px 0 45px}.hero h1{font-size:clamp(47px,11.6vw,69px);letter-spacing:-.055em}.eyebrow{font-size:11px;margin-bottom:20px}.hero-lower{grid-template-columns:1fr;margin-top:28px;gap:8px}.hero-description{font-size:19px;line-height:1.7}.hero-figure{max-width:300px;justify-self:end;width:85%;margin:0}.hero-figure canvas{height:150px}.meta{gap:15px;font-size:11px}.start-link{margin-top:15px}.chapter{padding:44px 0 18px}.chapter-heading{gap:13px;margin-bottom:26px}.chapter h2{font-size:32px}.lesson{grid-template-columns:1fr;gap:5px;padding-bottom:30px}.lesson h3{font-size:23px}.lesson p,.lesson li{font-size:18px;line-height:1.8}.sketch{position:static;max-width:290px;width:85%;justify-self:end;margin-top:4px;padding-top:0}.sketch canvas{height:158px}.sketch figcaption{font-size:12px}.chapter-intro{font-size:18px}.mobile-bar{padding:0 20px}.mobile-bar .author{font-size:14px}.contents-button{font-size:12px;padding:7px 9px}.stage-list li{grid-template-columns:95px 1fr;gap:12px}.closing{padding:48px 0 60px}.closing p{font-size:29px}.footer{flex-wrap:wrap;font-size:11px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}.sidebar{transition:none}}
/* Keep every chapter visible; only the current chapter's topics scroll. */
.rail-label{margin-bottom:28px}.contents-label{margin-bottom:10px}.chapter-nav{flex:none;overflow:visible}.nav-chapter{margin-bottom:0}.chapter-link{padding:8px 0}.topics-label{margin:24px 0 12px;font-size:11px;letter-spacing:.13em;text-transform:uppercase;color:var(--secondary)}.topic-nav{flex:1;min-height:0;overflow:auto;scrollbar-width:thin}.subnav{display:none;margin:0 0 6px 7px;padding-left:13px}.subnav.is-active{display:block}.rail-bottom{margin-top:18px;padding-top:16px}.sidebar{padding-bottom:20px}
@media(max-width:900px){.sidebar .subnav{display:none}.sidebar .subnav.is-active{display:block}.sidebar{width:min(330px,90vw)}.topics-label{margin-top:20px}}
@media(max-height:700px) and (min-width:901px){.sidebar{padding-top:22px}.rail-label{margin-bottom:18px}.chapter-link{padding:6px 0}.topics-label{margin-top:16px}.rail-bottom{padding-top:12px;margin-top:12px}.motion-toggle{margin-top:12px}}
/* Full contents stay available before and after unlocking. */
[hidden]{display:none!important}.book-locked .locked-chapter,.book-locked .book-only{display:none}.subnav,.sidebar .subnav{display:block!important;margin-bottom:22px}.subnav .topic-heading{font-size:12px;font-weight:600;color:var(--ink);margin-bottom:4px}.subnav.is-active .topic-heading{color:var(--blue)}.sample-label{font-size:10px;margin-left:auto;color:var(--secondary);font-weight:400}.chapter-link{gap:10px}.book-gate{display:grid;grid-template-columns:minmax(0,1fr) minmax(270px,.85fr);gap:54px;padding:70px 0 80px;border-bottom:1px solid var(--rule);scroll-margin-top:40px}.gate-copy h2{font-weight:500;font-size:clamp(38px,4.5vw,58px);line-height:1.08;letter-spacing:-.045em;margin:0 0 25px}.gate-copy>p:not(.eyebrow){font-family:Georgia,serif;font-size:19px;line-height:1.7;margin:0 0 20px}.gate-copy .gate-includes{color:var(--secondary);font-size:17px!important}.gate-copy .requested-topic{color:var(--blue);font-size:16px!important}.price-form{align-self:center;padding:29px;background:var(--rail);border:1px solid var(--rule);border-radius:6px}.price-form h3{font-size:25px;font-weight:500;letter-spacing:-.025em;margin:0 0 12px}.price-help{font-size:14px;line-height:1.6;color:var(--secondary);margin:0 0 20px}.price-options{display:flex;gap:9px;margin:0 0 24px}.price-options button{flex:1;font-size:16px;padding:11px 8px;border:1px solid #d8dce6;border-radius:3px;background:white}.price-options button[aria-pressed=true]{color:var(--blue);border-color:var(--blue);background:#edf1ff}.price-form label{display:block;font-size:13px;margin-bottom:9px}.price-field{position:relative;margin-bottom:20px}.price-field>span{position:absolute;left:14px;top:12px;font-size:19px;color:var(--secondary)}.price-field input{font:inherit;font-size:21px;width:100%;padding:10px 12px 10px 35px;border:1px solid #d8dce6;border-radius:3px;background:white;color:var(--ink)}.unlock-button{border:0;border-radius:3px;background:var(--blue);color:white;padding:14px 12px;width:100%;font-size:15px}.unlock-button:hover{background:#183cbd}.demo-note{font-size:12px;line-height:1.5;color:var(--secondary);text-align:center;margin:14px 0 0}.book-preview-status{display:flex;gap:16px;flex-wrap:wrap;align-items:center;justify-content:space-between;padding:13px 0;color:var(--secondary);font-size:13px;border-bottom:1px solid var(--rule)}.book-preview-status button{font-size:13px;color:var(--blue);border:0;background:none;padding:3px 0;text-decoration:underline;text-underline-offset:3px}
@media(max-width:1180px){.book-gate{gap:30px}.price-form{padding:22px}}
@media(max-width:900px){.book-gate{scroll-margin-top:95px}}
@media(max-width:600px){.book-gate{grid-template-columns:1fr;gap:22px;padding:45px 0 55px}.gate-copy h2{font-size:43px}.gate-copy>p:not(.eyebrow){font-size:18px}.price-form{padding:25px}.price-form h3{font-size:26px}.topic-nav{min-height:60px}}